Someone Else's Mastery Pages Bug

So I was in champion select and I was going to select my mastery page but for some reason they were completely different from the ones I use. For example, one was called "murderkaiser" and I have never played Mordekaiser before. There were also other pages that I had never created such as a page for Diana and a page for Nautilus. I never made those pages either seeing as how I don't own those champions (needless to say I was incredibly confused.) I decided to dodge in champion select and go fix them. Well for some reason they were back to normal when I went to edit them. I imagine this bug could cause problems for people when trying to play ranked and I've never seen this happen before, so I figured I should post it here.